I tried this 40-minute bodyweight core workout, and it strengthened my abs without a sit-up in sight

man doing side plank
(Image credit: Getty Images)

If you want to get better at running, you need a strong core, which is why the world’s best marathoners do this challenging core workout two or three times a week. Unlike most abs workouts, it doesn’t contain a single sit-up, but instead relies on long sets of leg raises and plank variations to improve your core endurance.

When I say the sets of each exercise are long, I mean long. I tried the workout and as a 2hr 27min marathoner myself I’m in pretty good shape, but I barely made it through any of the moves without an extra break or two. 

The workout is done by elite marathoners at Iten in Kenya, where it was filmed by running influencer Ben Felton for his YouTube channel, BenIsRunning. You can see Ben and a room of other runners following the workout, and he has added exercise names in the corner.

You’ll need an exercise or yoga mat for the workout, but otherwise it doesn’t require any equipment at all. It's important to do each move with proper technique to avoid arching your back, so it's worth using the demonstrations to perfect your form before you start. 

Watch Ben Felton's 40-minute core workout

The workout starts with a series of planks, mostly side planks variations, before a whole load of different types of leg raises and then core exercises for the lower back, which you do lying on your front.

You hold each plank for a minute, and then most of the moves afterwards are done to a count of 20. This count is done almost maliciously slowly by the instructor — you won’t believe how long he can stretch it out for at times.

Although the routine is hard, I did find it suitable for all levels, since taking an extra break during any set won't make it less effective — I still felt the benefits even with extra rests during most of the exercises after the planks at the start.

Just do what you can and rest for longer as required. If you can do it regularly, you'll quickly improve, though I don't see myself getting through all of the many leg raise variations without a break any time soon. 

I think the long sets involved are great for endurance runners in particular. I'm guilty of rushing through sets when strength training, but you can't do that with this workout, because the slow count from the instructor means you have to hold positions for longer, effectively strengthening those areas of the body to handle the rigors of long-distance running.

The workout finishes with some stretches, which are important to help you avoid any DOMS in the lower back in particular. The workout mostly targets your lower abs and the side muscles in your core, so you could add on this 10-minute standing abs workout if you want to hit the upper core muscles more.

If you’d rather take on a shorter session with equipment, this dumbbell abs workout takes just 25 minutes and only requires one set of weights. Or you can use adjustable dumbbells to quickly change the weight to make it appropriate to each exercise.

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Nick Harris-fry
Senior Writer

Nick Harris-fry is an experienced health and fitness journalist, writing professionally since 2012. He spent nine years working on the Coach magazine and website before moving to the fitness team at Tom’s Guide in 2024. Nick is a keen runner and also the founder of YouTube channel The Run Testers, which specialises in reviewing running shoes, watches, headphones and other gear.

Nick ran his first marathon in 2016 after six weeks of training for a magazine feature and subsequently became obsessed with the sport. He now has PBs of 2hr 27min for the marathon and 15min 30sec for 5K, and has run 13 marathons in total, as well as a 50-mile ultramarathon.

He runs 50-80 miles a week and races regularly with his club, which gives him a lot of opportunity to test out running gear: he has tested and reviewed hundreds of pairs of running shoes, as well as fitness trackers, running watches, sports headphones, treadmills, and all manner of other kit. Nick is also a qualified Run Leader in the UK.